In many industrial activities, workers require full facemasks mounted in hoods which rely on a separate air supply for respiration for protection. Many of these workers also require a full field vision to carry out their work effectively. Typical applications are with spray painters (deleterious solvents employed), welders (gas fuel and eyeburn risks from arc filtering) and surface blasters (sanders), who prepare corroded surfaces for recoating, painting, and the like.
In applications such as jet blasting, workman require both physical and respiratory protection from the particulate sanding material and loosened scale. The typical protective mask with its air intake passages and the outer viewing facepiece become clogged and obstructed. Practical operation requires that the pitted viewing lens be replaced with a new lens while working in the contaminated atmosphere. Protective upper body hoods, whether waist or shoulder length, are available to accomodate facemasks and their integrated breathing tubes and exhalation equipment.
One of the problems encountered in use of these protective masks is the difficulty in replacing the lens retainment under field conditions. Other problems include the inability to obtain a good seal to minimize grit ingestion and keeping the lens in place during use.
It is, therefore, an object of the invention to provide a lens and cartridge assembly for use with a standard protective facemask and associated abrasive blast hoods. It is another object to provide a lens cartridge assembly which can be replaced with a different configuration of lenses in the facepiece component with considerable ease when the existing unit has reached its limits of usefulness or specific service. It is still another object to provide a novel lens assembly which provides superior sealing against the invasion of grit from the outside into the breathing components of the external protective assembly.